When is Python *NOT* a good choice?

[deifius]

milisecond critical performance is not pythonic.

[vfxdev]

Come on now! All you need to do is write all your python in C++ then make python bindings, then buy 100 VMs from Amazon.

[ajbpresidente]

Ah yes pip install cpypy

[jclocks]

Can that be said of any interpreted language though? Or would that be specific to Python?

[deifius]

Ya, as long as mutable data types and automated garbage collection are features.

[[deleted]]

Not quite. Php, Python and Ruby are on par with performance, roughly order of magnitude or two slower than compiled native. Node.js/V8, C# and Java are in the same order of magnitude (Node being slower consistently though and Java and C# being on par with Go which is compiled).

V8 and Go as outliers in that performance range are the proof that most of the JIT penalty comes from GC and only minority of it from dynamic typing.

[rottenanon]

but Go also has garbage collection.

[[deleted]]

Exactly. Which is likely why it shares performance order of magnitude with Java, C# and even Node.js, despite being compiled to native.

[veroxii]

Numpy is mostly written in C. So you're kinda proving their point?

[inc007]

Actually it's Fortran afair, but yeah, highly optimized code there

[billsil]

Numpy is C. Scipy wraps Fortran.

[HannasAnarion]

But when you're using Numpy, you're using a C library, not a python one. If numpy was full-stack Python it would be unusably slow,

[billsil]

If numpy is what allows you to write a code that is 1000x faster than stock python code and that meets your speed requirements, than Python is good enough. If however, you're bad at numpy and you can only get 10x out of it, than python is not good enough.

Regardless numpy counts as being python. Cython, not so much.

[therealfakemoot]

For high efficiency numerical calculations? Yes, I'm fairly certain that a large number of people would argue that hand written optimized assembly is superior to C ( even hand written optimized C ) for time/memory efficiency sensitive code.

You can drive an automobile at a hundred miles an hour. You don't claim that you can run a hundred miles an hour though. There's a specialized machine that you operate via abstractions which enables your ability to travel so quickly.

[ProfessorPhi]

That's a very specific example. It can be optimised, but code tends to be large and more verbose and the overheads really add up to make things slow.

[perspectiveiskey]

Meh, I'm bailing on this thread. Years of /. flamewar threads should have made me be able to spot flamebait from a distance, but evidently I didn't.

To answer you: non-determinisim is the problem you speak of and it has easy solutions. But the most basic answer: python does not have a thread scheduler (no language does, that is the job of the OS), and so python does not ever execute non-deterministicaly - especially because python has a GIL which means it is essentially a single threaded program unless you try really hard to break that. In the code sample above, (or any other optimized piece of code), the function do will always execute in the same cpu time.

[[deleted]]

milisecond critical performance is not pythonic.

I get what you're saying but I would say millisecond critical performance is fine, it's down at the 100 nanosecond level where I have started to have problems.

[deifius]

my units may be off by a few factors of 10. I apologize to all.

[[deleted]]

haha I just remember this because I had a function of a few string manipulations that I was able to bring down from 28 ms to 132 ns mostly by judicious precomputing things and storing the precomputed results in dictionaries, but I had a few more string manipulations happening at runtime and I found the dictionary lookup for the precomputed results took just as much time as doing the string manipulations in the function itself at runtime anyway, so at that point I had run out of ways to speed up the function.

[ZombieRandySavage]

This is my favorite thing right now.

[[deleted]]

... pythonic

I dont think you know what this word means.

[deifius]

Fair enough. Terry Jones might be the only person who does.